Ambient noise cancellation for voice communication device

ABSTRACT

A system and method for reducing or entirely canceling background or ambient noise from a voice transmission from a communications device. A communications device, such as a mobile telephone, is configured with an ambient noise compensation signal generator that is connected between a first microphone and a mixer. A second microphone is employed to detect ambient noise. An original output of the first microphone and a compensation signal generated by the ambient noise compensation signal generator are mixed together prior to being passed to a transmitter. A buffer is provided between the microphone and the mixer to help synchronize the timing of the signals to be mixed and an output of the mixer is provided to an antenna.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/924,733 filed Jun. 24, 2013, now U.S. Pat. No.9,369,799, which is a continuation of and claims priority to U.S. patentapplication Ser. No. 12/246,348 filed Oct. 6, 2008, now U.S. Pat. No.8,472,641, which is a continuation of and claims priority to U.S. patentapplication Ser. No. 11/250,035 filed Oct. 13, 2005, now U.S. Pat. No.7,450,691, which is a continuation of and claims priority to U.S. patentapplication Ser. No. 10/101,715, filed Mar. 21, 2002, now U.S. Pat. No.6,978,010. The contents of U.S. patent application Ser. No. 13/924,733is/are hereby incorporated by reference into this application as if setforth herein in full.

FIELD OF THE DISCLOSURE

The present invention relates generally to voice communication and, morespecifically, to automated control to compensate for variable ambientnoise levels.

BACKGROUND OF THE DISCLOSURE

Voice communication devices such as mobile telephones have becomeubiquitous; they show up in almost every environment. They are used inthe home, at the office, in the car, on a train, at the airport, at thebeach, at restaurants and bars, on the street, and almost any otherimaginable venue. As might be expected, these diverse environments haverelatively higher and lower levels of background or ambient noise. Forexample, there is generally less noise in a quiet home than there is ina crowded bar.

Significantly, in an on-going telephone call from an environment havingrelatively higher ambient noise, it is sometimes difficult for the partyat the other end of the connection to hear what the party in the noisyenvironment is saying. That is, the ambient noise in the environmentoften “drowns out” the mobile telephone user's voice, whereby the otherparty cannot hear what is being said.

SUMMARY OF THE INVENTION

The present invention provides a novel system and method for monitoringthe ambient noise in the environment in which a voice communicationsdevice or mobile telephone is operating and canceling the ambient noisebefore the ambient noise is transmitted to the other party so that theparty at the other end of the voice communication link can more easilyhear what the mobile telephone user is transmitting.

The present invention preferably employs noise cancellation technologythat is operable to attenuate or even eliminate pre-selected portions ofan audio spectrum. By monitoring the ambient noise in the location inwhich the mobile telephone is operating and applying noise cancellationprotocols at the appropriate time, it is possible to significantlyreduce the background noise to which a party to a telephone call mightbe subjected.

It is therefore an object of the present invention to provide a systemand method that enhances the convenience of using a mobilecommunications device, even in a location having relatively loud ambientnoise.

It is also an object of the present invention to provide a system andmethod for canceling ambient noise before the ambient noise istransmitted to another party.

It is yet another object of the present invention to monitor ambientnoise via a second microphone associated with a mobile telephone andthereafter cancel the monitored ambient noise.

It is still another object of the present invention to provide anenable/disable switch on a mobile communications device toenable/disable the noise cancellation features of the invention.

These and other objects of the present invention will become apparentupon reading the following detailed description in conjunction with theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary mobile telephone including an optionalsecond microphone for sampling ambient noise and an enable/disablebutton in accordance with the present invention.

FIG. 2 illustrates an exemplary embodiment of the present invention.

FIG. 3 illustrates a second exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE DRAWINGS

The present invention provides a unique background noise or ambientnoise cancellation feature for a communications device such as a mobile(or cellular) telephone or even a conventional wire line telephone.While the present invention has applicability to at least these types ofcommunications devices, the principles of the present invention areparticularly applicable to all types of communications devices. Forsimplicity, the following description employs the term “mobiletelephone” as an umbrella term to describe the embodiments of thepresent invention, but those skilled in the art will appreciate that theuse of such term is not to be considered limiting to the scope of theinvention, which is set forth by the claims appearing at the end of thisdescription.

FIG. 1 illustrates an exemplary mobile telephone 10 that comprises amicrophone 11, a speaker 12, a display screen 13, a keypad 14 and anantenna 15. Optionally, a second microphone 16 for sampling ambientnoise level and an ambient noise compensation enable/disable button 17may also be provided. These latter two elements will be described morefully below. Those skilled in the art will appreciate that speaker 12could be replaced by an ear piece (not shown) that is worn by the mobiletelephone user in the conventional manner. Speaker 12 is used herein tomean the device by which sound is transferred from the mobile telephoneto the user. Also, display screen 13 could be a touch screen display,which might incorporate keypad 14 as well as enable/disable button 17.

FIG. 2 illustrates an exemplary embodiment of the present inventionincluding microphone 11, ambient noise compensation signal generator 20,a mixer 22, transmitter 24 and antenna 15.

In accordance with the present invention, ambient noise or backgroundnoise is cancelled before being combined with the intended voicecommunication picked up at microphone 11 and sent to transmitter 24 andantenna 15. More specifically, in a first embodiment, microphone 11picks up both ambient noise as well as the intended voice communication(together, the “combined signal”). As is well known in the art of noisecancellation, it is possible (e.g., via filtering and digital signalprocessing (DSP) techniques) to attenuate or even cancel-outpre-selected portions of an audio signal or pre-selected bands of afrequency spectrum.

As shown in FIG. 2, ambient noise compensation signal generator 20 isconnected to microphone 11 and monitors the combined signal. Then,ambient noise cancellation generator, in accordance with well-knowntechniques, generates compensation signals that are operable toattenuate or altogether cancel background noise that is not intended ordesirable to be transmitted to another party. These compensation signalsare fed into mixer 22 where these signals are mixed with the combinedsignal coining directly from microphone 11. The result is that theambient noise or background noise is eliminated, or at leastsubstantially reduced, before the combined signal (ambient noise plusvoice signal) is passed to transmitter 24 (which, e.g., includes a radiofrequency modulator, etc.) and ultimately to antenna 15.

Optionally, a buffer 28 is provided to slow the progress of the combinedsignal emanating from microphone 11 so that when the combined signalreaches mixer 22 the arrival time of the combined signal and thecompensation signals generated by ambient noise cancellation generatoris synchronized.

In another embodiment, as shown in FIG. 3, a second microphone 16 isprovided for the principal purpose of sampling ambient noise. That is,microphone 16 is dedicated substantially to picking up ambient noiserather than a voice signal. A second microphone, especially one that islocated away from mobile telephone user's mouth would be less affectedby the user's own voice when taking the ambient noise level measurementand, thus, might be more desirable in certain implementations of thepresent invention.

More specifically, it is often the case that microphone 11, which isused primarily for receiving voice signals from a user, is arranged tohave directional characteristics, wherein the microphone is moresensitive to sound coming from predetermined directions. In contrast,second microphone 16 is preferably omni-directional such that themicrophone is equally sensitive to sound emanating from any direction. Amore accurate detection of ambient noise level can be obtained usingsuch an omni-directional microphone. Also, although not shown expresslyin the drawings, microphone 16 could be arranged spatially distant frommobile telephone 10. For example, second microphone 16 could be arrangedto hang from a wire that is connected to mobile telephone 10, wherebythere would be even less chance for the mobile telephone user's voice tointerfere with noise cancellation signal generation.

Optionally, in the dual microphone embodiment, microphone 11 is also incommunication with ambient noise cancellation signal generator 20 toprovide additional signal information to generator 20 to aid indistinguishing more easily between ambient noise and voice signals.

Further in accordance with the present invention there is provided anenable/disable switch 17 (FIG. 1) that is preferably operable toenable/disable ambient noise compensation signal generator 20. Forexample, depending on the nature of the ambient noise in a particularenvironment, known noise cancellation techniques might alsoinadvertently attenuate the voice signal that is intended to betransmitted. In such a case, it is preferable that the noisecancellation features of the present invention be disabled, at least fora limited period, until the ambient noise is such that it can be moreeffectively distinguished from the voice signal and attenuatedindependently. For example, a mobile telephone user may want to call afriend from a noisy public event (e.g., a concert or sporting event) forthe main purpose of letting the friend hear the background noise. Insuch a case, the switch 17 is preferably manipulated to disable thenoise cancellation features of the present invention.

The foregoing disclosure of the preferred embodiments of the presentinvention has been presented for purposes of illustration anddescription. It is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Many variations andmodifications of the embodiments described herein will be obvious to oneof ordinary skill in the art in light of the above disclosure. The scopeof the invention is to be defined only by the claims appended hereto,and by their equivalents.

Further, in describing representative embodiments of the presentinvention, the specification may have presented the method and/orprocess of the present invention as a particular sequence of steps.However, to the extent that the method or process does not rely on theparticular order of steps set forth herein, the method or process shouldnot be limited to the particular sequence of steps described. As one ofordinary skill in the art would appreciate, other sequences of steps maybe possible. Therefore, the particular order of the steps set forth inthe specification should not be construed as limitations on the claims.In addition, the claims directed to the method and/or process of thepresent invention should not be limited to the performance of theirsteps in the order written, and one skilled in the art can readilyappreciate that the sequences may be varied and still remain within thespirit and scope of the present invention.

What is claimed is:
 1. A method comprising: detecting, by a firstmicrophone, a first signal containing voice signals and ambient noise;detecting, by a second microphone, a second signal containing theambient noise; receiving a noise cancellation signal indicating whetherto cancel the ambient noise; providing both the first signal detected bythe first microphone and the second signal detected by the secondmicrophone to an ambient noise compensation signal generator; responsiveto the noise cancellation signal indicating to cancel the ambient noise,enabling the ambient noise compensation signal generator to generate acompensation signal based on the first signal detected by the firstmicrophone and the second signal detected by the second microphone,wherein a mixer mixes the first signal detected by the first microphonewith the compensation signal such that the ambient noise contained inthe first signal detected by the first microphone is attenuated;responsive to the noise cancellation signal indicating not to cancel theambient noise, disabling the ambient noise compensation signalgenerator, wherein the mixer mixes the first signal detected by thefirst microphone with the second signal detected by the secondmicrophone, such that the ambient noise contained in the first signaldetected by the first microphone is not attenuated; buffering the firstsignal such that an arrival time of the first signal and thecompensation signal at the mixer is synchronized; and providing anoutput of the mixer to a transmitter.
 2. The method of claim 1, whereinthe mixer receives the first signal directly from the first microphone.3. The method of claim 1, wherein the first microphone is a directionalmicrophone that is sensitive to sound coming from a predetermineddirection, such that the voice signals are predominantly received by thefirst microphone.
 4. The method of claim 1, wherein the secondmicrophone is an omnidirectional microphone that is substantiallyequally sensitive to sound emanating from any direction, such that thevoice signals and the ambient noise are received by the secondmicrophone.
 5. The method of claim 1, wherein the ambient noise issubstantially eliminated before the output of the mixer is provided tothe transmitter.
 6. The method of claim 1, wherein the second microphoneis spatially distant from the first microphone.
 7. The method of claim6, wherein the first microphone is housed within a mobile telephone. 8.The method of claim 7, wherein the first microphone is positionedtowards a mouth of a user, and wherein the second microphone ispositioned away from the mouth of the user.
 9. The method of claim 8,wherein the second microphone is spaced apart from a housing of themobile telephone.
 10. The method of claim 9, wherein the secondmicrophone is arranged to hang from a wire attached to the mobiletelephone.
 11. The method of claim 1, further comprising modulating aradio frequency carrier based on the output of the mixer.
 12. The methodof claim 11, further comprising providing the output of the transmitterto an antenna.
 13. A communication device comprising: a first microphonethat provides a first signal containing voice signals and ambient noise;a second microphone that provides a second signal containing the ambientnoise; a switch that provides a noise cancellation signal indicatingwhether to cancel the ambient noise; an ambient noise compensationsignal generator in communication with the first microphone, the secondmicrophone and the switch, wherein the ambient noise compensation signalgenerator receives both the first signal detected by the firstmicrophone and the second signal detected by the second microphone andthe noise cancellation signal; a mixer in communication with the ambientnoise compensation signal generator, wherein: responsive to the noisecancellation signal indicating to cancel the ambient noise, the ambientnoise compensation signal generator generates a compensation signalbased on the first signal detected by the first microphone and thesecond signal detected by the second microphone, wherein the mixer mixesthe first signal detected by the first microphone with the compensationsignal such that the ambient noise contained in the first signaldetected by the first microphone is attenuated, and wherein, responsiveto the noise cancellation signal indicating not to cancel the ambientnoise, the ambient noise compensation signal generator is disabled,wherein the mixer mixes the first signal detected by the firstmicrophone with the second signal detected by the second microphone,such that the ambient noise contained in the first signal detected bythe first microphone is not attenuated; a buffer in communicationbetween the first microphone and the mixer, wherein the buffer delaysthe first signal such that an arrival time of the first signal and thecompensation signal at the mixer is synchronized; and a transmitter incommunication with an output of the mixer.
 14. The communication deviceof claim 13, wherein the first microphone is a directional microphonethat is sensitive to sound coming from a predetermined direction, suchthat the voice signals are predominantly received by the firstmicrophone.
 15. The communication device of claim 13, wherein the secondmicrophone is an omnidirectional microphone that is substantiallyequally sensitive to sound emanating from any direction, such that thevoice signals and the ambient noise are received by the secondmicrophone.
 16. The communication device of claim 13, wherein the secondmicrophone is spatially distant from the first microphone.
 17. Thecommunication device of claim 13, wherein the first microphone is housedwithin a mobile telephone.
 18. The communication device of claim 17,wherein the first microphone is positioned towards a mouth of a user,and wherein the second microphone is positioned away from the mouth ofthe user.
 19. The communication device of claim 18, wherein the secondmicrophone is spaced apart from a housing of the mobile telephone. 20.The communication device of claim 19, wherein the second microphone isarranged to hang from a wire attached to the mobile telephone.